With the ongoing development of micro-circuitry and multi-media technologies, digital cameras are now in widespread use. High-end portable electronic devices, such as mobile phones and PDAs (personal digital assistants), are being developed which are increasingly multi-functional. Therefore digital cameras now are popularly employed in portable electronic devices to allow the portable electronic devices to have an additional function of taking images and recording audiovisual information.
A typical digital camera includes a lens module for capturing optical information of an object and an image sensor for sensing the optical information captured by the lens module. Usually, an aperture is a necessary optical element in the lens module and is used for controlling an amount of light passing through the lens module. In FIGS. 6-8, a conventional mechanical aperture 100 is shown. The mechanical aperture 100 includes a number of arc laminas 110. The arc laminas 110 are movable so that a central through hole 120 having a predetermined diameter can be formed. The diameter of the central through hole 120 can be adjusted by moving the arc laminas 100 for controlling the amount of light passing through the aperture 100. However, the movement of the arc laminas 110 generally requires the assistance of a number of mechanical components, which renders the aperture 100 unduly bulky and therefore limits the application of lens module incorporating such an aperture 100 in a portable electronic devices.
What is needed, therefore, is an aperture with a compact configuration and a variable aperture size.